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Ohio State University Extension


C.O.R.N. Newsletter 2008-32

Dates Covered: 
September 22, 2008 - September 30, 2008
Wesley Haun

Information on Harvesting Downed Corn

Authors: Randall Reeder, Peter Thomison

As a result of the high winds associated with Hurricane Ike on September 14, we’ve received many questions about lodged corn and best approaches for harvesting downed corn. There are several good informational sources available to provide specific tips for equipment and operational management to minimize harvest losses.

Lodged Corn 2008 - webpage created by the University of Kentucky which is
a clearinghouse for information related to lodged corn with links to articles, tools, etc. related to harvesting lodged corn. Available online at

Nielsen, R.L. (Bob). 2008. References for Harvesting Lodged Corn. Corny News Network, Purdue Univ. [On-line]. Available at

Greg Roth, Penn State University, has tips for harvesting down corn. This web site also has a list of 8 companies that sell equipment for picking up downed corn:

Sam McNeil, University of Kentucky Extension Ag. Engineer, summarized cost comparisons for harvesting down corn at higher moistures and using heated-air drying:

Dale Hicks, University of Minnesota, has information on harvesting corn at an angle to the rows, matching the direction of lodging:

Marion Calmer of Calmer Corn Heads, Inc. listed 18 tips for harvesting down corn. Most are specific adjustments or minor changes to the corn head:

Safety will be an issue this fall. Because of down corn, harvest will drag on longer than usual, the header will plug more often, and operator stress and frustration will be high. Under these conditions it is more important than ever to emphasize safety. Perhaps tape safety reminders at various places (in the combine cab, truck cab, and dryer area, for example). When a problem arises, count to 10 before exiting the combine cab.

Operating in a safe, deliberate manner may extend harvest by a week or two. That may seem excessive, but compare it to the delay that could result from a major injury.

Fall Herbicide Treatments in Wheat – Burndown or Early POST

Authors: Mark Loux

For the past several years, we have emphasized the importance of a preplant/preemergence application of glyphosate in no-tillage wheat. Many winter annual weeds have emerged by early October, and they can be effectively controlled with relatively low rates of glyphosate prior to wheat emergence. This can be a more effective treatment for winter annuals, compared to the herbicides that can be applied broadcast to wheat in late fall or early spring. Producers who have applied glyphosate at the time of no-till wheat planting report that their fields have been relatively free of winter annuals in the spring. Preemergence application of glyphosate is also an effective and inexpensive tool to control winter annual grasses such as downy brome and cheat. A dense population of winter annuals may have already suppressed wheat growth by the time a spring treatment can be applied. In addition, our research over the past 8 years or so in various crops has led us to the general conclusion that herbicides are most consistently effective on winter annuals when applied in fall. The effectiveness of spring treatments can be extremely variable due to wide swings in weather conditions and the possibility of a late spring.

We have previously suggested that glyphosate applied at this time of the year could provide some of the better control of dandelion in wheat, but producers have indicated that this has not necessarily been the case. While we know that late September is somewhat early for optimum dandelion control, our recommendation was based on the known variability of spring herbicide treatments on dandelion. Late fall herbicide treatments to emerged wheat may be another option that is more effective for dandelion control. We conducted a study last fall and spring to compare various herbicide treatments on dandelion in wheat. This is only one year of data, and we’ll be conducting the study again this year, but the results highlight some of the more effective treatments as well as the issues with dandelion control in spring.

Fall treatments were applied in mid-November, and spring treatments were applied in early April. Results shown here are from a May 13 evaluation. At that time, dandelion control from fall treatments ranged from 63 to 97%, while control from spring treatments ranged from 43 to 78%. Express (0.33 oz/A) was a common component of the most effective treatments in fall or spring. Express plus dicamba (4 oz product/A) applied in the fall resulted in 97% dandelion control the following spring. This treatment also effectively controlled the winter annual weeds in the field. Several other treatments resulted in this level of control, but were more expensive. Examples – WideMatch + dicamba; WideMatch + Express; WideMatch + Harmony Extra. We did not apply the combination of Harmony Extra + dicamba in the fall, since Express is more effective on dandelion than Harmony Extra. Only one spring-applied treatment provided better than 70% control of dandelion - WideMatch + Express + 2,4-D.

We did not apply 2,4-D in the fall, due to its potential to injure wheat and reduce yield. We did apply a premix product that contained dicamba and 2,4-D in fall and spring, but this treatment was less effective than any of the others. We were not able to measure wheat yield at the study location, but we will be able to do so when we repeat the study this year. The results of this study indicate that one approach to dandelion and winter annual weed management may be to skip the preemergence glyphosate treatment, and instead apply herbicides in November to emerged wheat. This may not be the right approach in fields with a history of winter annual grass problems or other perennial weeds that are in the right stage for control by late September. We hope to get a better comparison for dandelion control between the preemergence glyphosate application and the late fall herbicide treatments in the second year of the study.

A final note on burndown - at this time of the year we start to receive questions about the safety and legality of 2,4-D applied prior to wheat planting. We do not know of any 2,4-D product labels that support this use of 2,4-D. There is some risk of stand reduction and injury to wheat from preplant applications of 2,4-D. We question why producers would want to use 2,4-D, when glyphosate can be applied for about the same cost to obtain a similar level of weed control (better on some species). One argument in favor of the use of 2,4-D would be to avoid overuse of glyphosate and slow the development of herbicide resistance. However, 2,4-D can be used with glyphosate in fall and spring herbicide treatments prior to corn and soybean planting, and would probably be best avoided prior to wheat planting.

Farm Safety – Protect YOUr Investment

Authors: Dee Jepsen

The National Safety Council has declared the week of September 21 – 27, 2008 as National Farm Safety and Health Week. This annual promotional week commemorates the hard work, diligence, and sacrifices made by our nation’s farmers and ranchers.

This year’s safety theme is “Farm Safety – Protect YOUr Investment.” As the message implies, personal well-being is important to the long-term sustainability of the farm operation.
On average, 27 Ohio farmers lose their life each year while working on the farm. That adds up to 276 people every decade. These fatalities are caused by accidental injury.

However, behind the injuries statistics lurk an even larger number of health concerns. Hearing, respiratory conditions, vision, skin, and the musculo-skeletal system are affected daily by the hard work and harsh environments the body endures while performing farm work. Ask anyone involved in agriculture, and they will tell you that farming is physically hard work. That physical wear and tear takes it toll in many ways.

For the most part, farming is perceived as a healthy lifestyle. However, farm living also has several environmental and occupational hazards that are inherent to the daily routines. So take the necessary precautions, and “Protect YOUr Investment!”

Fall Cutting of Alfalfa

Authors: Mark Sulc

Every year many Ohio alfalfa producers take a fall cutting. Unfortunately, cutting alfalfa in late September to mid-October can carry serious risk to the health of the stand. Cutting during this period interrupts the process of storage of energy and proteins in alfalfa taproots. When alfalfa is cut during this period and if soil moisture is adequate, the plant will regrow and utilize those precious taproot energy and protein reserves that are needed for winter survival and spring regrowth next year.

Fall cutting may not result in real obvious stand loss, although that can occasionally happen. The more common occurrence is for fall-cut alfalfa stands to suffer some loss of vigor and yield next year that is not so obvious. One could only see such loss of vigor and yield next year if side-by-side comparisons were made within the same field, where strips of alfalfa are cut or not cut this fall. Often, the yield gained by fall cutting is lost in reduced yields the following year.

I realize that some producers are in need of additional hay supplies this year. So how can they minimize the potential for damage from cutting alfalfa stands this fall?

A LATE fall harvest is a safer alternative than cutting now in late September to mid-October, By LATE HARVEST, I mean as close as possible to a killing frost of alfalfa, which happens when air temperatures reach 25 F for several hours. This often does not happen until sometime in November in Ohio. BUT I recommend this late harvest option ONLY IF the soil is well-drained, the stand is healthy, a variety is planted that has excellent winterhardiness, and the soil has good fertility status.

I know that the weather is usually lousy in November for cutting forage, but waiting to get closer to the killing frost will prevent the late fall regrowth that “burns up” energy reserves. Thus, cutting late when fall regrowth is less likely will reduce the risk of loss of vigor next spring.

A fall harvest after a killing frost is relatively safe IF the soil is well-drained and there is no history or risk of heaving on that particular soil. Without residue cover, the temperature at the soil surface will fluctuate more, so the potential for heaving injury is greater.

I am often asked whether leaving a large amount of fall growth can harm the alfalfa stand in the winter. The fear is that the alfalfa will “smother itself out”. I have let pure stands of alfalfa go into the winter with a lot of growth, even more than we see this fall, and I have never experienced a problem or seen the crop “smother out”.

Fall management of alfalfa is one of the few controllable factors that will potentially influence the health of your alfalfa stand next year. It could play a determining role in how much yield you get next year. If you don’t need the forage, walk away from it this fall and let it insulate those alfalfa crowns this winter. The stand won’t smother out because of excessive alfalfa growth.

If you do need the forage now and to get through this winter, then taking a cutting in early November or after a killing frost will reduce the risk of injury to the stand. But try to limit late cutting of alfalfa to well-drained soils with good pH and fertility status. Also leave a 6-inch stubble.

Finally, if you do cut alfalfa this fall, leave several different strips or areas within the same field where you do not cut. You might learn something interesting next spring about fall cutting on your farm.

Prussic Acid Poisoning Potential in Frosted Forages

Authors: Mark Sulc

Jack Frost will certainly arrive this autumn in Ohio, bringing the potential for prussic acid poisoning when feeding specific forage species. Some species, primarily sorghums and closely related species, contain cyanogenic glucosides, which are converted quickly to prussic acid in freeze-damaged plant tissue.

Animals can die within minutes of ingesting forages with high concentrations of prussic acid, also known as hydrogen cyanide. Prussic acid binds to hemoglobin in the bloodstream and interferes with oxygen transfer, causing animals to die of asphyxiation. Symptoms include excess salivation, difficult breathing, staggering, convulsions, and collapse. Ruminants are more susceptible than horses or swine because cud chewing and rumen bacteria help release the cyanide from plant tissue.

Sudangrass varieties are low to intermediate in cyanide poisoning potential, sudangrass hybrids are intermediate, sorghum-sudangrass hybrids and forage sorghums are intermediate to high, and grain sorghum is high to very high.

Johnsongrass, chokecherry, black cherry, indiangrass, elderberry, and some varieties of birdsfoot trefoil also have potential for prussic acid poisoning. Piper sudangrass has low prussic acid poisoning potential, and pearl millet and foxtail millet have very low levels of cyanogenic glucosides.

Plants growing under high nitrogen levels or in soils deficient in phosphorus or potassium will be more likely to have high cyanide potential. After frost damage, cyanide levels will likely be higher in fresh forage as compared with silage or hay, because cyanide is a gas and dissipates as the forage cures and dries.

Young, rapidly growing plants of species with prussic acid poisoning potential will have the highest levels of prussic acid, as the cyanide is more concentrated in young leaves than in older leaves or stems. New growth of sorghum species following drought or frost is dangerously high in cyanide. Pure stands of indiangrass (not common in Ohio), if grazed when the plants are less than 8 inches tall, can have lethal levels of cyanide.

When grazing or greenchopping species with prussic acid potential this fall, follow these guidelines:
• Do not graze on nights when frost is likely. High levels of the toxic compounds are produced within hours after a frost.
• Do not graze after a killing frost until plants are dry, which is usually 5 to 7 days.
• After a non-killing frost, do not allow animals to graze for two weeks because the plants usually contain high concentrations of toxic compounds. New growth may appear at the base of the plant after a non-killing frost. If this occurs, wait for a hard, killing freeze then wait 10 to 14 days before grazing.
• Don’t allow hungry or stressed animals to graze young growth of species with prussic acid potential.
• Graze or greenchop only when sudangrass exceeds 18 inches in height, and sorghum-sudangrass should be 30 inches in height before grazing. Never graze immature growth at any time.
• Do not graze wilted plants or plants with young tillers.
• Green-chopping the frost-damaged plants will lower the risk compared with grazing directly, because animals have less ability to selectively graze damaged tissue; however, the forage can still be toxic, so feed with great caution. Feed greenchopped forage within a few hours, and don’t leave greenchopped forage in wagons or feedbunks overnight.

When making hay or silage from sorghum species this fall, consider the following:
• Prussic acid content decreases dramatically during the hay drying process and the forage should be safe once baled as dry hay. The forage can be mowed anytime after a frost. It is very rare for dry hay to contain toxic levels of prussic acid. If the hay was not properly cured, it should be tested for prussic acid content before feeding.
• Forage that has undergone silage fermentation is generally safe to feed. To be extra cautious, wait 5 to 7 days before chopping after the forage was frosted. If the plants appear to be drying down quickly after a killing frost, it can safely be ensiled within a shorter time period from the frost.
• Delay feeding silage for 8 weeks after ensiling. If the forage likely contained high HCN levels at time of chopping, hazardous levels of prussic acid might remain and the silage should be analyzed before feeding.

Other common forages such as alfalfa, clovers, and cool-season perennial grasses do NOT produce toxic compounds after a frost and can be fed safely. The only concern is a slightly higher potential for bloat when grazing legumes within a day or two after a killing frost.

Testing for Prussic Acid Content in Forages

Authors: Mark Sulc

The previous topic describes management practices to follow for feeding sorghum species to livestock after a frost. If doubt remains regarding the safety of the forage, the forage can be tested for prussic acid (HCN) content. But keep in mind that prussic acid is a gas, so it is difficult to detect in samples sent to labs. Sample handling is extremely critical to ensure that the lab test will be representative of what is being fed to livestock.

Obtain a representative FRESH sample of the forage to be fed. Collect 1 to 2 lbs of fresh forage from across the field to be grazed. For silage, follow proper sampling protocol to obtain a representative sample.

Do not allow the sample to dry. Place in an air-tight plastic bag, freeze the sample, and ship the fastest way (overnight express) in a cooler with an ice pack.

Remember, HCN content dissipates with drying of the sample. So if the sample arrives at the lab drier than the fresh forage that is fed, a false negative result will likely occur.

The following are two labs that will analyze samples as soon as they arrive. Other labs may provide testing for prussic acid, always call ahead to confirm whether the prussic acid test is provided.

The Michigan State University Animal Health laboratory
Diagnostic Center for Population and Animal Health
Michigan State University
4125 Beaumont Road
Lansing, MI 48910-8104
TEL (517) 353-1683, FAX (517) 353-5096
Request Procedure 70022

Midwest Laboratories
13611 B Street
Omaha, NE 68144-3693
TEL (402) 334-7770, FAX (402) 334-9121

Weather Report

Authors: Jim Noel

Expect the dry weather to continue. There may be light showers in eastern Ohio by the weekend as a system moves up the east coast, otherwise below normal rainfall will continue. Above normal temperatures are expected this week and below normal temperatures next week.

The outlook into October appears to be near normal temperatures and below normal rainfall.

Archive Issue Contributors: 

State Specialists: Ann Dorrance, Pierce Paul, and Dennis Mills (Plant Pathology), Peter Thomison (Corn Production), Mark Loux (Weed Science), Mark Sulc (Forage Production), Randall Reeder and Dee Jepsen (Food, Agricultural, and Biological Engineering), James Noel (NOAA/NWS/OHRFC). Extension Agents and Associates: Roger Bender (Shelby), Harold Watters (Champaign), Mike Gastier (Huron), Howard Siegrist (Licking), Les Ober (Geauga), Wesley Haun (Logan), Steve Foster (Darke), Todd Mangen (Mercer), Gary Wilson (Hancock), Glen Arnold (Putnam), Greg LaBarge (Fulton), Bruce Clevenger (Defiance), Marissa Mullet (Coshocton), Steve Bartels (Butler), Suzanne Mills-Wasniak (Montgomery)., Jonah Johnson (Clark), and Tim Fine (Miami).

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.